Alkaline storage battery

Abstract

An alkaline storage battery includes a positive electrode. The positive electrode includes a positive electrode mixture. The positive electrode mixture contains a nickel compound and a metal compound. The nickel compound is a positive electrode active material The metal compound is a compound of at least one metal element selected from the group consisting of titanium, niobium, tungsten, vanadium, molybdenum, zirconium, and tantalum. A ratio Wm/Wn of a mass Wm of the metal compound contained in the positive electrode mixture to a mass Wn of the nickel compound contained in the positive electrode mixture in terms of nickel hydroxide ranges from 0.2/100 to 5.0/100. The metal compound contains iron at a mass ratio ranging from 10 ppm to 10000 ppm. A ratio We/Wp of a mass We of the alkaline electrolyte to a mass Wp of the positive electrode mixture ranges from 0.35 to 1.0.

1 . An alkaline storage battery comprising a positive electrode, a negative electrode, a separator disposed between the positive electrode and the negative electrode, and an alkaline electrolyte, wherein
 the positive electrode includes a positive electrode current collector and a positive electrode mixture supported by the positive electrode current collector,   the positive electrode mixture contains a nickel and a metal compound, the nickel compound being a positive electrode active material,   the metal compound is a compound of at least one metal element selected from the group consisting of titanium, niobium, tungsten, vanadium, molybdenum, zirconium, and tantalum,   a ratio Wm/Wn ranges from 0.2/100 to 5.0/100 where Wm is a mass of the metal compound contained in the positive electrode mixture, and Wn is a mass of the nickel compound contained in the positive electrode mixture in terms of nickel hydroxide,   the metal compound contains iron at a mass ratio ranging from 10 ppm to 10000 ppm, and   a ratio We/Wp ranges from 0.35 to 1.0, where We is a mass of the alkaline electrolyte and Wp is a mass of the positive electrode mixture.   
     
     
         2 . The alkaline storage battery according to  claim 1 , wherein
 the positive electrode, the negative electrode, and the separator are stacked on one another and wound to form a wound assembly,   the negative electrode includes a negative electrode current collector and a negative electrode mixture layer disposed on the negative electrode current collector,   the negative electrode mixture layer contains a hydrogen-absorbing alloy,   an outermost circumference of the negative electrode in the wound assembly is located outer than an outermost circumference of the positive electrode in the wound assembly, and   a mass of the hydrogen-absorbing alloy per a unit area in the outermost circumference of the negative electrode is smaller than a mass of the hydrogen-absorbing alloy per a unit area in a part of the negative electrode other than the outermost circumference of the negative electrode.   
     
     
         3 . The alkaline storage battery according to  claim 2 , wherein a thickness of the negative electrode mixture layer in the outermost circumference of the negative electrode is thinner than a thickness of the negative electrode mixture layer in a part of the negative electrode mixture layer inner than the outermost circumference of the negative electrode. 
     
     
         4 . The alkaline storage battery according to  claim 2 , wherein
 the negative electrode is wound such that the negative electrode mixture layer in the outermost circumference of the negative electrode has a first portion that is disposed on an outer side of the negative electrode current collector and a second portion that is disposed on an inner side of the negative electrode current collector, and   a thickness of the first portion of the negative electrode mixture layer is thinner than a thickness of the second portion of the negative electrode mixture layer.   
     
     
         5 . The alkaline storage battery according to  claim 1 , wherein
 the alkaline electrolyte contains sodium hydroxide and potassium hydroxide,   a concentration of the sodium hydroxide in the alkaline electrolyte is higher than a concentration of the potassium hydroxide in the alkaline electrolyte.   
     
     
         6 . The alkaline storage battery according to  claim 1 , wherein the alkaline electrolyte contains sodium hydroxide and does not contain potassium hydroxide.